第四章 微生物燃料电池 第二节 MFC结构

第四章微生物燃料电池第一节微生物燃料电池概述第二节微生物燃料电池的材料与结构第三节微生物燃料电池的应用第四节微生物燃料电池的进展方向微生物燃料电池的材料与结构†ThemainchallengeinconstructinganMFCisfirsttoidentifymaterialsandarchitecturesthatmaximizepowergenerationandCoulombicefficiency,butthenextchallengeistominimizecostandcreatearchitecturesthatareinherentlyscalable.†ThemainthreecomponentsoftheMFCaretheanode,cathode,andifpresent,themembrane.Theanodehasreachedthehighestlevelofdevelopmentwiththeadventofgraphitefiberbrushelectrodes.UsingmembranesormaterialsthatmayseparateanodesandcathodesisagreatchallengeforMFCsduetotheirhighcostandtheirgeneraleffectofincreasinginternalresistance.Thecriticalpropertyofacathode,whichisdifferentfromtheanode,istheneedforacatalyst.However,recentresearchshowsseveralpromisingapproachesforreplacingpreciousmetalcatalystswithtransitionmetalandothernon-precious-metalcompounds.Anodematerial†Therequirementsofananodematerialare:highlyconductive,non-corrosive,highspecificsurfacearea(areapervolume),highporosity,non-fouling(ie.,thebacteriadonotfillitup),inexpensive,andeasilymadeandscaledtolargersizes.†Carbonpaper,cloth,foams,andRVC.Theuseofcarbon-basedelectrodesinpaper,cloth,andfoamformsfortheMFCanodeisverycommon.微生物燃料电池的结构†AlargerangeofmaterialshavebeenusedinMFCs,assummarizedinthepreviouschapter.Howthesematerialsarepacked,arranged,andusedinthefinalsystemdesignwhatisreferredtohereasthereactorarchitecture-ultimatelydictateshowthesystemwillperformintermsofpoweroutput,Coulombicefficiency,stability,andlongevity.Singlechamberair-cathodecubesystem†Cubereactors.AusefulandsimpledesignforexaminingfactorsthataffectpowerproductioninMFCswasanair-cathodereactordevelopedatPennState(LiuandLogan2004).Thisthesingle-chamber,air-cathodecubereactorhasbeenhasbeenusedandreportedoninoveradozenpublicationsTwo-chamberair-cathodesystem.NewbottlereactorMFC†Moreexperimentalworkisbeingdonewithpurecultures,necessitatingasystemwhichcanbeeasilyautoclavedandkeptsterile.Abottletypeofsingle-chamber,air-cathodereactorwasdevelopedandtestedusingbothpureandmixedcultures.Thereactorconsistsofastandardlaboratorymediabottlemodifiedtocontainasidearm.Essentiallyonebottleofatwo-chamberedreactor,withthesidearmofalargerdiameterthantypicallyused.Thesidearmismadewithalargerdiametertoincreaseoxygentransfertothecathode,whichisheldbetweenthesidearmandasmalladditionaltubeextension.SinglechambercubesystemSCMFC†Forseveralyearsithadbeenshownthatelectricitycouldbegeneratedfromwastewater,butthefirstdemonstrationofsuccessfulwastewatertreatment(i.e.,CODorBOD)withelectricitygenerationwasdemonstratedbyLiuetal.(2004)usinganovelMFCreactordesign.†Theyconstructedatubular-typeofsingle-chamber,air-cathodeMFCthathadacathodeinsertedinthecenterofanacrylictube,witheightgraphiterodsarrangedinaconcentricmatteraroundthecathode.ThecathodewasmadebyhotpressingaCEM(Nafion)tocarboncloth,andwrappingtheclotharoundatubedrilledwithholestoallowoxygentransfertothecathodesurface.Theeightrodswereconnectedtothecathodewithasinglewire.FlatPlateMFCSingle-chumberreactorwithgraphite-metalcathodeLargerreactorsThesimplestMFCdesignconsistsoftwochambersseparatedbyacationexchangemembrane(CEM).Thedistinguishingfeaturesofthesesystemsaretwochambers,theCEM,andacathodesuspendedinwaterthatisspargedwithair.Theconcentrationofdissolvedoxygencanaffectperformance(Ohetal.2004),withpowerdecreasingasDOisloweredorincreasingifpureoxygenisused.Theanodechambercanalsobespargedwithgas(forexample,withnitrogentoremoveoxygen),althoughsomebacteriamaybeadverselyaffectedbytheshearcreatedbythegasbubbling.国内几个装置试样†上课结束位置†AdifferentapproachhasbeenusedbySchroderandco-workersbasedonusingbacterialfermentationtogenerateH2gas,withtheH2reactingontheanodecontainingachemicalcatalysttoproduceelectronsandprotons.ThesetypesofH2-basedsystemsarereallyhydrogenfuelcellsashydrogenreactsattheanode,butbecausebacteriaarepresentinthesystem,theycanalsobeconsideredatypeofMFC.MiniaturereactorsPilotMFC